Bird strikes can down airliners but are mass culls the answer?

Mardi, Avril 18, 2017

Safety fears have led to mass culls of birds near airports. But are such drastic measures necessary?

In January 2009, in a “miracle” on the Hudson river, a stricken airliner ditched on the water with no loss of human life. But it was no miracle for the birds of New York, which were blamed for the accident. Research has suggested that nearly 70,000 gulls, starlings, geese and other birds have been killed since then, mostly by shooting, trapping, and in some cases, such as Prospect Park, gassing. Some campaigners have accused airports worldwide of a “post-Hudson panic” leading to the deaths of millions of birds.

“We were all very used to the geese in Prospect Park,” says Jeffrey Kramer, a volunteer for GooseWatchNYC. This group of wildlife “vigilantes” was founded in 2010 to encourage alternatives to the ineffective and inhumane culling of geese in New York City’s parks. “Then we woke up one morning with a lake covered in feathers where there used to be hundreds of geese.” Wildlife officials had taken the geese to a hangar at Kennedy Airport, where they were gassed.

In the UK, according to the Civil Aviation Authority (CAA), the number of confirmed bird strikes rose from 1,496 to 1,665 between 2011 and 2015. Only in 6 per cent of cases did it have some kind of operational effect on an aircraft. In many of these incidents, planes aborted take-off, returned to the airport, or diverted to another.

According to Nature England, 12,956 birds were culled in 2015-16. Rooks, crows and pigeons made up the largest number. With numbers of bird strikes rising despite culls, protesters are demanding that the authorities use less barbaric ways of keeping the skies safe. While the technology to do this regularly hits the headlines, it rarely seems to reach the tarmac.

Avian radar is a case in point. It can track flocks of birds and has been used by the military for decades. It has helped the Israeli air force to reduce bird strikes by two-thirds. Why isn’t technology like this more widely used at commercial airports?

A bird’s eye view

“Everyone knows that bird strikes are a problem that is not going away,” says Kramer. “The protesters and the cullers all acknowledge that killing isn’t the answer. Technology caused the problem, so technology will have to solve it.”

Professor John Swaddle, a bird ecologist, says: “It’s not a lack of technology that has prevented the problems of bird strikes being solved, it’s a lack of science. It’s a lack of basic understanding of the birds’ point of view.”

Swaddle, a visiting research associate at Exeter University, has developed the sonic net, a technology by which noise is played at the same pitch as the alarm calls of birds or predator noises they are listening out for – and, as a result, it becomes a lot riskier for them to hang around. Rooks are among the birds most at risk Rooks are among the birds culled most often to help reduce strikes at British airports.

According to some, the problem is already being managed. “Airports in general are doing a good job. The problem with birds is that they adapt very quickly,” says Stephen Landells, a safety specialist at the British Airline Pilots’ Association. “Airports are realising that you have to have a load of measures in place, and I think they are doing that quite successfully, because you don’t see many planes crashing.”

A spokesman for the CAA says: “The CAA considers airport habitat management practices across the UK to be effective at managing the bird strike hazard, and as a result the number of serious bird strike incidents that occur in the UK is relatively low.”

Others think the issue is more profound. “There is a human-wildlife conflict here,” says Jess Chappell, a policy officer at the RSPB. “We are encroaching on more and more wildlife habitats. It is a case of learning to live with wildlife rather than killing everything.”

Why bird strikes have become a big problem

Bird strikes are as old as aviation itself. One of the first recorded collisions between a bird and an aircraft was in 1908. The first human death occurred in 1912, when a gull collided with a wooden Wright Flyer. In those days, aeroplanes flew at much slower speeds and birds, by and large, had time to get out of their way. The invention of the jet engine changed all that.

Today, a bird may hit a commercial airliner’s cockpit window, dent its fuselage or be sucked into its engine – causing expensive ground checks and delays. If a plane collides with a whole flock of birds, then the damage can be a great deal more severe. They may take out an engine or more – and then, as in the landing on the Hudson it will come down to the skill of the pilot and the cleverness of the computers to prevent disaster.

For the bird, the collision is usually fatal; its DNA may be all that is left to identify what species it was. For humans, it is less dangerous, with 25 deaths attributed to bird strikes in the US between 1990 and 2013.

The solutions attempted so far…

One of the first attempts at scaring birds away from runways was the humble scarecrow. Today, while all airports have a bird management plan, their techniques don’t seem to be very different. These can include playing bird calls, killing individual birds, playing loud noises and flashing lights, and even live-capture and relocation.

This is often accompanied by “habitat management”. Cruder versions of this include netting over ponds and even, in China, training monkeys to destroy nests. Some airports grow long grass that is unattractive to birds.

The failure of such techniques has been used to justify the continuation of culling – even though culls, many critics suggest, merely help the airports look as if they are doing something. Now, inspired by nature, a new generation of solutions is being proposed, from drones that look like birds of prey through to low-level laser beams that the birds see as a physical object that they want to stay away from and don’t get used to, and Swaddle’s sonic net.

Yet even these are not without problems – real or imagined. The birds may quickly learn that a drone isn’t actually a hawk, while the lasers could blind a bird as they could an airline pilot; and it’s difficult to develop a sonic device that works with all bird species at the same time. Despite its use by the military, avian radar has been criticised for requiring specialist staff and for not identifying specific species – although some types of avian radar can.

“There is lots of work going into novel ways of dealing with this problem. Lasers seem to be effective,” says Chappell.

After successful trials at a small airport in the US, where there was an 80 per cent reduction in the numbers of birds, Swaddle’s sonic net is set for a trial at a large airport in Singapore later this year. “When birds experience this they either leave the area or their vigilance goes up because they can’t hear each other’s alert calls or a predator coming,” says Swaddle.

“Unlike with other technologies, its effectiveness didn’t diminish over time. This is because not being able to hear predators is a real threat.

“In the end, to really manage these bird issues the technologies used are going to have to be complementary, like avian radar and the sonic net. I doubt that there will ever be a ‘silver bullet’ that will solve all the problems.”